Geotechnical Risks and Management Systems: An FHWA Perspective

Transcription

1 October 13, STGE Conference Charleston, WV Geotechnical Risks and Management Systems: An FHWA Perspective Silas C. Nichols, PE, Senior Bridge Engineer - Geotechnical Federal Highway Administration Benjamin S. Rivers, PE, Geotechnical Engineer Federal Highway Administration

2 Competing Demands

3 Geotechnical Management Slope Management Systems Geohazard Management Systems Retaining Wall Inventories and Management Management of Geotechnical Systems & Appurtenances Mechanically stabilized systems - Rock-bolts/anchors, dowels/soil-nails Drainage systems Rock-fall mitigation systems Ground improvements Geotechnical Data Management Systems

4 Natural and Man-made Conditions affecting Slopes and Infrastructure

5 Hazard vs. Risk (Threat) Hazards Earthquake Hurricane Abandoned Underground Mines Karst Geology Landslides Rockfall Risks Earthquake occurs a) resulting in fatalities. b) resulting in major injuries. c) Resulting in disruption of lives. d) damage to property

6 Risk Management Limit Surprises Minimize Management by Crisis Operate Proactively instead of Reactively Reduce Long-term Costs Increase Likelihood of Success Do It Right the First Time Prevent or Minimize Bad Things from Happening Optimize Designed Solutions Minimize Threats Maximize Opportunities

7 Slope Failure Impacts and Management Threats Closure Impedance to Mobility Economic Impact to Region & Users Cost of Repair/Remediation Injury and damages Loss of Life Obstacles Resources (time, money, people) Convincing Decision Makers Proactive Funding Mechanism Mitigating Off-ROW threats before failure

8 Slope Management Systems Motivation - ECONOMICS Problem of frequency and severity Costs often poorly tracked, but known to be great Seldom have funding to address all problems No one size fits all strategy available

9 Slope Management Systems Limitations Do not solve problem rather provides information needed to address problem most effectively Do not establish optimum strategy rather enables implementation of selected strategy Are not self-sustaining require maintenance and upgrades (funding and manpower!)

10 Slope Management System Database Type Geology Traffic INVENTORY DATA COLLECTION Means & Methods Responsibility Characteristics -Slope -Highway/traffic -Slide Consequences RATING

11 Slope Characteristics Information ODOT 1992 ODOT 2001 NYDOT 1992 WSDOT 1993 Ohio DOT 2006 NH DOT TN DOT Height Geology Groundwater

12 Highway/Traffic Characteristics Information ODOT 1992 ODOT 2001 NYDOT 1992 WSDOT 1993 Ohio DOT 2006 NH DOT TN DOT ADT Classification Speed Detour time Site distance Travel distance

13 Slide Characteristics Information ODOT 1992 ODOT 2001 NYDOT 1992 WSDOT 1993 Ohio DOT 2006 NH DOT TN DOT Volume Emergency Frequency Deformation rate Scarp dimensions

14 Consequences Information ODOT 1992 ODOT 2001 NYDOT 1992 WSDOT 1993 Fatalities Ohio DOT 2006 NH DOT TN DOT Vehicle risk Damage Road impact Annual cost History Cost/benefit Future impact

15 Other Features Incorporate into GIS and integrated data layers (site info, photos, topographic, geologic maps, Google Earth Pro, etc.) Integrated Geologic Structure and Geotechnical Data Profiling Data Distinguish between modes of failure Condition assessments/performance monitoring of slopes and appurtenances (i.e. condition of rock-bolts/dowels, drains, mesh, fences, etc.) Effectiveness of Ditch (Catchment) Mitigation Cost

16 Example: NH DOT Rockcut Management System

17 Costs and Economic Strategies Costs depend on Size and severity of problem condition Maintenance/repair technique(s) used Site location Availability of equipment and materials Whether contracted or inhouse Degree of improvement achieved Economic Strategies Minimize costs Immediate costs Life-cycle costs Minimize risk Minimize total cost Maximize value

18 Take-Aways Realistic Scope - Functional & Maintainable System Support of Upper Management and Necessary Designated Resources Clearly convey risks and benefits Value-Added & Representation of Geotechnical Engineering FHWA Initiatives Guidance framework for slope/geotechnical management systems Integration of Asset Management Life-cycle considerations of geotechnical features and systems Integration of Geotechnical Data Management Distinction between Hazard and Risk Groundwork for Standard of Practice

19 Questions?